Projection systems are known for rendering images for projection onto a surface such as a screen. When projecting onto a projection surface that has markings on it, feedback loops can be used to align images with the markings. For example, systems using calibration patterns that are visible or invisible are known for aligning multiple projectors or for autofocusing projectors. In general, these systems use an algorithm that performs an iterative process.
Projecting content onto non-traditional screens is also known. For example, there are systems for projecting images onto the ground or the floor of a building. In general, such systems merely use the other surface as a screen and require a uniform surface onto which the content is to be projected.